Heating means



Patented Aug. 22, 1939 UNITED STATES PATENT OFFICE 15 Claims.

This invention relates to heating means, more particularly to heating means having surfaces constructed and arranged to transfer heat from heat-producing means, such as for instance, an electric resistance element, and the principal object of this invention is to provide new and improved heating means of this type.

In the drawing accompanying this specification, and forming a part of this application, there are shown, for purposes of illustration, several forms which this invention may assume, and in this drawing:

Figure 1 is a fragmentary plan view of a strip or blank used in an embodiment of the invention,

Figure 2 is a fragmentary perspective view of the blank shown in Figure 1, bent to a shape assumed just prior to assembly with the heating member,

Figure 3 is a transverse section through the heating member, showing the embodiment of the invention in position about the member, one of the connections being shown in open relation,

Figure 4 is an enlarged fragmentary plan view, looking from the right of Figure 3, illustrating various positions of the connecting fingers during the stages of assembly,

Figures 5 and 6 are views similar to Figure 2, but showing the blank bent somewhat differently,

Figures 7 and 8 are fragmentary plan views of portions of blanks similar to that shown in Figure 1, but provided with connecting fingers of a different shape,

Figures 9 through 11 show various ways of connecting the blanks, and

Figure 12 is a diagrammatic View showing an arrangement of the heating means herein disclosed.

Referring to Figures 1 through 4, the embodiment of the invention therein shown comprises a plurality of connected strips, each strip having folds providing means for transferring heat from a heating member, the strips forming a covering or sheath closely fitting the outer surface of the heating member, as best shown in Figure 3. The strips may be similar in construction, thereby necessitating the use of only one die in forming these strips, and in Figure 1 is shown a strip or blank I5, punched out of a sheet of heatconductive material, such as sheet-metal. The strip I5 comprises a plurality of integrally connected portions I6, opposite margins of the strip I5 being notched intermediate adjoining portions, as shown at IT. Fingers l8 and I9 are formed on the opposite margins of the strip I5,

these fingers being positioned intermediate the length of each portion I6.

Each of the fingers I8 comprises a generally straight part 28 extending from the marginal surface of the respective portion, an intermediate inclined part 2I, and a generally straight end part 22. Each of the fingers I9 comprises a generally straight part 23, and an inclined part 24, this latter part inclining in a direction opposite to the inclination of the part 2! of the finger I8. Each of the portions I6 is formed with an embossing 25, for a purpose which will be apparent later.

The portions I6 are adapted to be bent along lines indicated by the dash lines 26 and 27, the bends along the lines 26 folding contiguous parts of adjoining portions I6 upon each other to form heat-transfer surfaces or fins 28, whereas the bends along lines 21 form angular integral connections betweenthe fins 28, as best shown in Figure 2.

The parts 28 and 23 of the fingers I8 and I9 respectively, are curved to extend in the same direction, and the finger I8 is additionally bent along dash lines 29 and 38 to a generally step formation as best seen in Figure 2, whereas the portion 24 of the finger I9 is bent along dash lines 3| to extend angularly from the curved. portion 23.

A complementary strip I5a may be formed in accordance with the description of the strip I5. In some instances, as in the present case, the embossing 25 may be omitted from the strip I5a. It will be obvious that strips, such as the strips I5 and I 5a, may be readily formed in great quantities by the use of a continuous punch press.

The strips I5 and l5a are adapted to form a sheath or covering about heat-producing means, such as the electric resistance heating member 32 shown in Figures 3 and 4. The element 32 is formed of a sheet-metal channel 33, a plate 34 closing the opening of the channel. As seen in Figure 3, this construction provides a longitudinal recess 35 in the outer surface of the heating memher. A suitable electric resistance is disposed within the heating member 32, such as a resistance of the ribbon type, as shown at 36, this electrical resistance being imbedded in suitable refractory material 31.

To assemble the strips I5 and I5a with the heating member 32, the strip I501 is positioned so that its fingers I9 will align with the fingers I8 of the strip I5, the curved parts 20 and 23 of the respective fingers I8 and I9 being proportioned to closely fit about the edge surfaces of the heating member 32. In this position, the inclined parts 2| and 24 of the respective fingers I8 and I9 overlie each other, but are in a somewhat staggered relation, as best seen in Figure 4, the parts 24 of the fingers l9 ending adjacent the end parts 22 of the fingers l8, and these end parts 22 are then bent or clinched over the parts 24, so as to provide a connection of a generally unbroken character. From the foregoing, it will be obvious that projections at the ends of the heating members, such as terminal blocks or the like, will not interfere with the assembly of the parts carrying the heat-transfer fins.

Referring to Figure 3, it will be seen that the embossings 25 are so formed as to lie'within the recess 35 of the heating member 32, and to,

contact the outer surface of the plate 34, so that the covering or sheath formed by the strips l5 and Mia is in heat-conducting relation with substantially the entire outer surface of the heating member 32. a

In some instances, it is desirable to change the size of the heat-transfer surfaces or fins 28, and this change in size is readily made possible by bending the strips l5 and 15a along lines spaced from the dash lines 21. As an illustration, the heat-transfer surfaces 28 in Figure 5 have been formed by bending along lines similar to the lines 21, but spaced nearer the dash lines 26, the result being that the fins 28 extend a lesser distance away from the heating member 32, and these fins are spaced a greater distance apart. Additionally, it will be obvious that the overall length of the strip, when bent, will vary as the size of the heat-transfer surfaces, the overall length being increased in the construction shown in Figure 5, as compared to the construction shown in Figure 2.

To increase the exposed surface of the radiating fins 28, the strip may be bent along the lines 26 in a manner similar to that hereinbefore described, with the exception that the bending is stopped before the adjacent surfaces are folded upon each other. The fins 28 in this case then assume a generally V-shape, as best seen in Figure 6, with the adjacent surfaces in spaced-apart relation. Forming the fins in the manner shown in Figure 6 will also increase the length of the bent strip, as compared to the construction shown in Figure 2. Where it is necessary to provide varying degrees of heat-transfer at different portions of the heating member, the heat-transfer surfaces 28 may be made of a lesser or greater size, or may be formed as shown in Figure 6, at different portions of the heating member, as the condition demands. 7 I

Figure 7 shows a fragmentary portion of strips or blanks 38, 38a, Which are similar to the strips l5, l5a, with the exception that the fingers 39 and 48 are formed entirely straight, that is without inclined parts such as the parts 2| and 24 previously described. In this case, the fingers 39 and 40 interlock in substantially the same manner as that described in connection with the fingers l8 and I9, and it will be apparent that a Space 4| will beformed intermediate each of the connected fingers. Heat-transfer surfaces or fins 42, are formed and positioned substantially similar to the surfaces 28. InFigure'8the strips 38 and 38a have been displaced with respect to each other, so that the finger 39 of the strip 38 is out of alignment with the finger 40 of the strip 38a. Interengagement of the fingers 39 and. 40, in this construction,

provides a connection of a generally unbroken character. Also, in this construction, it will be obvious that the heat-transfer surfaces 42 on the strip 38 will be in staggered relation with respect to the surfaces 42 on the strip 38a.

The seams formed by the interengaging fingers shown in Figures 1 through 8 may be at diagonal corners, as shown diagrammatically in Figure 9, or these seams may both be at one face, as shown diagrammatically in Figure 10. The seams shown in Figures 1 through 10 may be not only crimped closed, but additionally connected by spot welding, line welding, riveting, bolting, or the like.

.-The crimp may be omitted, as shown diagrammatically in Figure 11, and in this case, strips- 41, 48, similar to the strips [5, l5a hereinbefore described, are provided only with stub portions 49, 50, which may be secured to each other by spot welding,'line welding, riveting, bolting, or the like. It will be apparent that stub portions may take the place of the crimped fingers shown in Figures 9 and 10.

Figure 12 diagrammatically illustrates a plurality of heating members adapted to be arranged in a heating apparatus to heat a fluid, such as air, moving in a direction of the arrows 5|. It will be noted that the heat-transfer surfaces are formed only on the longer opposite sides of each heating member, and in line with the flow of air. The other opposite sides of the heating member are relatively small in size and offer little resistance to the flow of air, these other opposite sides being substantially free of any projections, so that a larger number of heating members may be arranged in a bank in line with the flow of air.

It will be understood by those skilled in the art that I have accomplished at least the principal object of my invention, and at thesame time it will be obvious that the embodiments of my invention herein disclosed and described embody advantages other than those particularly pointed out or suggested herein, and that they may be variously changed and. modified without departing from the spirit of my invention or sacrificing the advantages thereof; accordingly it will be understood by those skilled in the art that thedisclosure herein is illustrative only, and that my invention is not limit-ed thereto.

I claim:

1. Heating means, comprising: heat-producing means; a plurality of metallic strips, each having heat-transfer fins, and each being formed with fingers at opposite marginal edges, the fingers of one strip being adapted to interlock with the fingers of an adjacent strip, so that said strips form a sheath closely receiving said heat-producing means, said fingers being so constructed and-arranged, that when interlocked, said fingers form a substantially unbroken connection between said strips.

2. Heating means, comprising: heat-producing means; heat-conductive means, engaging the outer surface of said heat-producing means, and having opposed edges, each formed with projection means, the projection means of one edge having at least portions out of alignment with the projection means of the other edge, said projection means being connected, holding said heatconductive means to said heat-producing means, the out of alignment portions providing that the connection between said opposed edges is of a substantially unbroken nature.

3. Heating means, comprising: heat-producing means; heat-conductive means, engaging the outer surface of said heat-producing means, and

with the projection means of the other edge, said projection means being connected, holding said heat-conductive means to said heat-producing means, the out of alignment portions providing a substantially unbroken connection between said opposed edges.

4. Heating means, comprising: an elongated heating member; at least two metallic strips extending longitudinally of said heating member, and of a combined Width to substantially embrace said heating member transversely, said strips having opposed edges, each formed with fingers; the fingers of one edge having at least portions out of alignment with the fingers of the other edge; said fingers being so bent to form a. connection between said strips, holding said strips in position on said heating member, and said out of alignment portions providing that said connection is of a substantially unbroken nature.

5. Heating means, comprising: an elongated heating member; at least two metallic strips extending longitudinally of said heating member and of a combined width to substantially embrace said heating member transversely, said strips having opposed edges, each formed with fingers spaced apart a distance less than the width of a finger; the fingers of one edge being positioned generally in alignment with the space between the fingers of the other edge; and the fingers of one edge being bent over the fingers of the other edge, forming a substantially unbroken connection between said strips, and holding said strips in position on said heating member.

6. Heating means, comprising: an elongated heating member; at least two metallic strips, each comprising a plurality of similar connected portions, contiguous parts of adjoining portions being folded to form heat-transfer fins, and intermediate parts of said portions providing integral connections between said fins, at least certain of said intermediate parts being formed with extending fingers on opposite edges; said strips being arranged longitudinally of said heating member, with said fins extending transversely with respect to said heating member, the fingers of one strip having at least portions out of alignment with the adjacent fingers of another strip, and the fingers of one strip being bent over the fingers of the other strip, providing a substantially unbroken connection between said strips, and holding said strips in position on said heating member.

7. Heating means, comprising: heat-producing means; heat-conductive means, held in heatconducting relation with respect to said heat-producing means, and comprising an elongated metallic strip having notches in opposite longitudinal margins, portions of said strip on opposite sides of a transverse line joining certain notches being bent to form heat-transfer fins, and portions of said strip intermediate said fins engaging said heat-producing means.

8. Heating means, comprising: heat-producing means; heat-conductive means, held in heatconducting relation with respect to said heat-producing means, and comprising an elongated metallic strip having generally transversely aligned notches in opposite longitudinal margins, and fingers extending from said opposite margins intermediate said notches, portions of said strip being folded together along transverse lines joining aligned notches, and folded again intermediate said first named fold and the portion of said strip aligned with said fingers, forming a plurality of heat-transfer fins, said fingers being bent around said heat-producing means, holding said strip to said heat-producing means.

9. Heating means, comprising: heat producing means, the outer surface of which has a depressed portion; heat-conductive means, in heat-conducting relation with the outer surface of said heat-producing means, and comprising an elongated strip bent to provide a plurality of heattransfer fins, portions of said strip intermediate said fins engaging the outer surface of said heatproducing means, and at least certain of said portions being formed to fit within the depressed portion of the outer surface of said heat-producing means.

10. Heating means, comprising: heat-produc ing means; heat-conductive means, engaging the outer surface of said heat-producing means in heat-conducting relation, and comprising a sheath-like covering about said heat-producing means, having a plurality of bends forming heattransfer fins; said fins being substantially equal to a transverse dimension of said heat-producing means.

11. Heating means, comprising: an elongated electric heating element; a plurality of metallic strips, each extending longitudinally of said heating element and comprising a plurality of similar connected portions, contiguous parts of adjoining portions being folded to form heat-transfer fins extending transversely, but generally Within a transverse dimension of said heating element, and intermediate parts of said portions providing integral connections between said fins; the marginal edges of said strips, at said intermediate parts, being connects forming a sheath-like covering embracing said heating element.

12. Heating means, comprising: an elongated electric heating element having a generally rectangular oblong cross-section; two metallic strips, each extending longitudinally of said heating element, and each of a width substantially equal to the wider surfaces of said heating element, each of said strips comprising a plurality of similar connected portions, contiguous parts of adjoining portions being folded transversely to form heat-transfer fins, and intermediate parts of said portions providing integral connections between said fins, and being transversely extended on opposite margins to form fingers constructed and arranged to extend around the narrower surfaces of said heating element, the extremity of fingers on adjacent edges of said strips interlocking, holding said strips in position on said heating element.

13. Heating means, comprising: an elongated electrical heating element; sheet metal heat transfer means, mounted on and engaging the outer surface of said element, and comprising a plurality of longitudinally spaced transverse bends, the sides of said bends projecting laterally from said heating element and forming heat transfer fins which at least at said surface of said heating element are of a dimension, transverse to said element, at most not materially greater than the transverse dimension of said element.

14. Heating means, comprising: an elongated electric heating element; a plurality of metallic strips, each extending longitudinally of said heat- 75 ing element and being so bent as to comprise a plurality of longitudinally spaced portions in engagement with a surface of said heating element, and so bent as to comprise a plurality of transverse bends respectively intermediate said spaced portions, the sides of said bends projecting laterally from said heating element and forming heat transfer fins which at least at the junctions of the sides of said bends and said spaced portions are of a dimension, transverse to said element, at most not materially greater than the transverse dimension of said heating element adjacent said junctions; and said spaced portions of respective strips being connected so as to hold said strips assembled with said heating element.

15. Heating means, comprising: an elongated electric heating element having a generally reotangular oblong cross-section; two metallic strips, each extending longitudinally of said heating element, at opposite wider sides of said heating element, and being so bent as to comprise a plurality of longitudinally spaced portions in engagement with the respective wider sides of said heating element, and so bent as to comprise a plurality of transverse bends respectively intermediate said spaced portions, the sides of said bends projecting laterally from said heating element and forming heat transfer fins which at least at the junctions of the sides of said bends and said spaced portions are of a dimension, transverse to said element, at most not materially greater than the respective wider sides of said heating element adjacent said junctions; and said spaced portions of respective strip-s being connected so as to hold said strips assembled with said heating element.

EDWIN L. WIEG-AND. 

